codegen: separate getAnonDeclVAddr into lowerAnonDecl and the former

Implement the stub for Elf.

I believe that separating the concerns, namely, having an interface
function that is responsible for signalling the linker to lower
the anon decl only, and a separate function to obtain the decl's
vaddr is preferable since it allows us to handle codegen errors
in a simpler way.

5 files changed, 123 insertions, 66 deletions

diff --git a/src/link/Coff.zig b/src/link/Coff.zig
index 8aebd0de6a..bfd7c9da46 100644
--- a/src/link/Coff.zig
+++ b/src/link/Coff.zig
@@ -1727,13 +1727,8 @@ pub fn getDeclVAddr(self: *Coff, decl_index: Module.Decl.Index, reloc_info: link
     return 0;
 }
 
-pub fn getAnonDeclVAddr(
-    self: *Coff,
-    decl_val: InternPool.Index,
-    reloc_info: link.File.RelocInfo,
-) !u64 {
-    // This is basically the same as lowerUnnamedConst except it needs
-    // to return the same thing as `getDeclVAddr`
+pub fn lowerAnonDecl(self: *Coff, decl_val: InternPool.Index, src_loc: Module.SrcLoc) !codegen.Result {
+    // This is basically the same as lowerUnnamedConst.
     // example:
     // const ty = mod.intern_pool.typeOf(decl_val).toType();
     // const val = decl_val.toValue();
@@ -1744,6 +1739,13 @@ pub fn getAnonDeclVAddr(
     // ...
     _ = self;
     _ = decl_val;
+    _ = src_loc;
+    _ = @panic("TODO: link/Coff lowerAnonDecl");
+}
+
+pub fn getAnonDeclVAddr(self: *Coff, decl_val: InternPool.Index, reloc_info: link.File.RelocInfo) !u64 {
+    _ = self;
+    _ = decl_val;
     _ = reloc_info;
     _ = @panic("TODO: link/Coff getAnonDeclVAddr");
 }
diff --git a/src/link/Elf.zig b/src/link/Elf.zig
index eff720eac4..a9a4757883 100644
--- a/src/link/Elf.zig
+++ b/src/link/Elf.zig
@@ -155,12 +155,14 @@ last_atom_and_free_list_table: std.AutoArrayHashMapUnmanaged(u16, LastAtomAndFre
 /// value assigned to label `foo` is an unnamed constant belonging/associated
 /// with `Decl` `main`, and lives as long as that `Decl`.
 unnamed_consts: UnnamedConstTable = .{},
+anon_decls: AnonDeclTable = .{},
 
 comdat_groups: std.ArrayListUnmanaged(ComdatGroup) = .{},
 comdat_groups_owners: std.ArrayListUnmanaged(ComdatGroupOwner) = .{},
 comdat_groups_table: std.AutoHashMapUnmanaged(u32, ComdatGroupOwner.Index) = .{},
 
 const UnnamedConstTable = std.AutoHashMapUnmanaged(Module.Decl.Index, std.ArrayListUnmanaged(Symbol.Index));
+const AnonDeclTable = std.AutoHashMapUnmanaged(InternPool.Index, Symbol.Index);
 const LazySymbolTable = std.AutoArrayHashMapUnmanaged(Module.Decl.OptionalIndex, LazySymbolMetadata);
 
 /// When allocating, the ideal_capacity is calculated by
@@ -321,6 +323,7 @@ pub fn deinit(self: *Elf) void {
         }
         self.unnamed_consts.deinit(gpa);
     }
+    self.anon_decls.deinit(gpa);
 
     if (self.dwarf) |*dw| {
         dw.deinit();
@@ -348,13 +351,8 @@ pub fn getDeclVAddr(self: *Elf, decl_index: Module.Decl.Index, reloc_info: link.
     return vaddr;
 }
 
-pub fn getAnonDeclVAddr(
-    self: *Elf,
-    decl_val: InternPool.Index,
-    reloc_info: link.File.RelocInfo,
-) !u64 {
-    // This is basically the same as lowerUnnamedConst except it needs
-    // to return the same thing as `getDeclVAddr`
+pub fn lowerAnonDecl(self: *Elf, decl_val: InternPool.Index, src_loc: Module.SrcLoc) !codegen.Result {
+    // This is basically the same as lowerUnnamedConst.
     // example:
     // const ty = mod.intern_pool.typeOf(decl_val).toType();
     // const val = decl_val.toValue();
@@ -363,10 +361,44 @@ pub fn getAnonDeclVAddr(
     // be used by more than one function, however, its address is being used so we need
     // to put it in some location.
     // ...
-    _ = self;
-    _ = decl_val;
-    _ = reloc_info;
-    _ = @panic("TODO: link/Elf getAnonDeclVAddr");
+    const gpa = self.base.allocator;
+    const gop = try self.anon_decls.getOrPut(gpa, decl_val);
+    if (!gop.found_existing) {
+        const mod = self.base.options.module.?;
+        const ty = mod.intern_pool.typeOf(decl_val).toType();
+        const val = decl_val.toValue();
+        const tv = TypedValue{ .ty = ty, .val = val };
+        const name = try std.fmt.allocPrint(gpa, "__anon_{d}", .{@intFromEnum(decl_val)});
+        defer gpa.free(name);
+        const res = self.lowerConst(name, tv, self.rodata_section_index.?, src_loc) catch |err| switch (err) {
+            else => {
+                // TODO improve error message
+                const em = try Module.ErrorMsg.create(gpa, src_loc, "lowerAnonDecl failed with error: {s}", .{
+                    @errorName(err),
+                });
+                return .{ .fail = em };
+            },
+        };
+        const sym_index = switch (res) {
+            .ok => |sym_index| sym_index,
+            .fail => |em| return .{ .fail = em },
+        };
+        gop.value_ptr.* = sym_index;
+    }
+    return .ok;
+}
+
+pub fn getAnonDeclVAddr(self: *Elf, decl_val: InternPool.Index, reloc_info: link.File.RelocInfo) !u64 {
+    const sym_index = self.anon_decls.get(decl_val).?;
+    const sym = self.symbol(sym_index);
+    const vaddr = sym.value;
+    const parent_atom = self.symbol(reloc_info.parent_atom_index).atom(self).?;
+    try parent_atom.addReloc(self, .{
+        .r_offset = reloc_info.offset,
+        .r_info = (@as(u64, @intCast(sym.esym_index)) << 32) | elf.R_X86_64_64,
+        .r_addend = reloc_info.addend,
+    });
+    return vaddr;
 }
 
 /// Returns end pos of collision, if any.
@@ -3126,50 +3158,68 @@ fn updateLazySymbol(self: *Elf, sym: link.File.LazySymbol, symbol_index: Symbol.
 
 pub fn lowerUnnamedConst(self: *Elf, typed_value: TypedValue, decl_index: Module.Decl.Index) !u32 {
     const gpa = self.base.allocator;
-
-    var code_buffer = std.ArrayList(u8).init(gpa);
-    defer code_buffer.deinit();
-
     const mod = self.base.options.module.?;
     const gop = try self.unnamed_consts.getOrPut(gpa, decl_index);
     if (!gop.found_existing) {
         gop.value_ptr.* = .{};
     }
     const unnamed_consts = gop.value_ptr;
-
     const decl = mod.declPtr(decl_index);
-    const name_str_index = blk: {
-        const decl_name = mod.intern_pool.stringToSlice(try decl.getFullyQualifiedName(mod));
-        const index = unnamed_consts.items.len;
-        const name = try std.fmt.allocPrint(gpa, "__unnamed_{s}_{d}", .{ decl_name, index });
-        defer gpa.free(name);
-        break :blk try self.strtab.insert(gpa, name);
+    const decl_name = mod.intern_pool.stringToSlice(try decl.getFullyQualifiedName(mod));
+    const index = unnamed_consts.items.len;
+    const name = try std.fmt.allocPrint(gpa, "__unnamed_{s}_{d}", .{ decl_name, index });
+    defer gpa.free(name);
+    const sym_index = switch (try self.lowerConst(name, typed_value, self.rodata_section_index.?, decl.srcLoc(mod))) {
+        .ok => |sym_index| sym_index,
+        .fail => |em| {
+            decl.analysis = .codegen_failure;
+            try mod.failed_decls.put(mod.gpa, decl_index, em);
+            log.err("{s}", .{em.msg});
+            return error.CodegenFail;
+        },
     };
+    const sym = self.symbol(sym_index);
+    try unnamed_consts.append(gpa, sym.atom_index);
+    return sym_index;
+}
+
+const LowerConstResult = union(enum) {
+    ok: Symbol.Index,
+    fail: *Module.ErrorMsg,
+};
+
+fn lowerConst(
+    self: *Elf,
+    name: []const u8,
+    tv: TypedValue,
+    output_section_index: u16,
+    src_loc: Module.SrcLoc,
+) !LowerConstResult {
+    const gpa = self.base.allocator;
+
+    var code_buffer = std.ArrayList(u8).init(gpa);
+    defer code_buffer.deinit();
 
+    const mod = self.base.options.module.?;
     const zig_module = self.file(self.zig_module_index.?).?.zig_module;
     const sym_index = try zig_module.addAtom(self);
 
-    const res = try codegen.generateSymbol(&self.base, decl.srcLoc(mod), typed_value, &code_buffer, .{
+    const res = try codegen.generateSymbol(&self.base, src_loc, tv, &code_buffer, .{
         .none = {},
     }, .{
         .parent_atom_index = sym_index,
     });
     const code = switch (res) {
         .ok => code_buffer.items,
-        .fail => |em| {
-            decl.analysis = .codegen_failure;
-            try mod.failed_decls.put(mod.gpa, decl_index, em);
-            log.err("{s}", .{em.msg});
-            return error.CodegenFail;
-        },
+        .fail => |em| return .{ .fail = em },
     };
 
-    const required_alignment = typed_value.ty.abiAlignment(mod);
-    const shdr_index = self.rodata_section_index.?;
-    const phdr_index = self.phdr_to_shdr_table.get(shdr_index).?;
+    const required_alignment = tv.ty.abiAlignment(mod);
+    const phdr_index = self.phdr_to_shdr_table.get(output_section_index).?;
     const local_sym = self.symbol(sym_index);
+    const name_str_index = try self.strtab.insert(gpa, name);
     local_sym.name_offset = name_str_index;
-    local_sym.output_section_index = self.rodata_section_index.?;
+    local_sym.output_section_index = output_section_index;
     const local_esym = &zig_module.local_esyms.items[local_sym.esym_index];
     local_esym.st_name = name_str_index;
     local_esym.st_info |= elf.STT_OBJECT;
@@ -3179,21 +3229,20 @@ pub fn lowerUnnamedConst(self: *Elf, typed_value: TypedValue, decl_index: Module
     atom_ptr.name_offset = name_str_index;
     atom_ptr.alignment = required_alignment;
     atom_ptr.size = code.len;
-    atom_ptr.output_section_index = self.rodata_section_index.?;
+    atom_ptr.output_section_index = output_section_index;
 
     try atom_ptr.allocate(self);
+    // TODO rename and re-audit this method
     errdefer self.freeDeclMetadata(sym_index);
 
     local_sym.value = atom_ptr.value;
     local_esym.st_value = atom_ptr.value;
 
-    try unnamed_consts.append(gpa, atom_ptr.atom_index);
-
     const section_offset = atom_ptr.value - self.phdrs.items[phdr_index].p_vaddr;
-    const file_offset = self.shdrs.items[shdr_index].sh_offset + section_offset;
+    const file_offset = self.shdrs.items[output_section_index].sh_offset + section_offset;
     try self.base.file.?.pwriteAll(code, file_offset);
 
-    return sym_index;
+    return .{ .ok = sym_index };
 }
 
 pub fn updateDeclExports(
diff --git a/src/link/MachO.zig b/src/link/MachO.zig
index 3786eccba9..10e6c614de 100644
--- a/src/link/MachO.zig
+++ b/src/link/MachO.zig
@@ -2840,13 +2840,8 @@ pub fn getDeclVAddr(self: *MachO, decl_index: Module.Decl.Index, reloc_info: Fil
     return 0;
 }
 
-pub fn getAnonDeclVAddr(
-    self: *MachO,
-    decl_val: InternPool.Index,
-    reloc_info: link.File.RelocInfo,
-) !u64 {
-    // This is basically the same as lowerUnnamedConst except it needs
-    // to return the same thing as `getDeclVAddr`
+pub fn lowerAnonDecl(self: *MachO, decl_val: InternPool.Index, src_loc: Module.SrcLoc) !codegen.Result {
+    // This is basically the same as lowerUnnamedConst.
     // example:
     // const ty = mod.intern_pool.typeOf(decl_val).toType();
     // const val = decl_val.toValue();
@@ -2857,6 +2852,13 @@ pub fn getAnonDeclVAddr(
     // ...
     _ = self;
     _ = decl_val;
+    _ = src_loc;
+    _ = @panic("TODO: link/MachO lowerAnonDecl");
+}
+
+pub fn getAnonDeclVAddr(self: *MachO, decl_val: InternPool.Index, reloc_info: link.File.RelocInfo) !u64 {
+    _ = self;
+    _ = decl_val;
     _ = reloc_info;
     _ = @panic("TODO: link/MachO getAnonDeclVAddr");
 }
diff --git a/src/link/Plan9.zig b/src/link/Plan9.zig
index ba333c666c..5355e19e1b 100644
--- a/src/link/Plan9.zig
+++ b/src/link/Plan9.zig
@@ -1418,13 +1418,8 @@ pub fn getDeclVAddr(
     return undefined;
 }
 
-pub fn getAnonDeclVAddr(
-    self: *Plan9,
-    decl_val: InternPool.Index,
-    reloc_info: link.File.RelocInfo,
-) !u64 {
-    // This is basically the same as lowerUnnamedConst except it needs
-    // to return the same thing as `getDeclVAddr`
+pub fn lowerAnonDecl(self: *Plan9, decl_val: InternPool.Index, src_loc: Module.SrcLoc) !codegen.Result {
+    // This is basically the same as lowerUnnamedConst.
     // example:
     // const ty = mod.intern_pool.typeOf(decl_val).toType();
     // const val = decl_val.toValue();
@@ -1435,6 +1430,13 @@ pub fn getAnonDeclVAddr(
     // ...
     _ = self;
     _ = decl_val;
+    _ = src_loc;
+    _ = @panic("TODO: link/Plan9 lowerAnonDecl");
+}
+
+pub fn getAnonDeclVAddr(self: *Plan9, decl_val: InternPool.Index, reloc_info: link.File.RelocInfo) !u64 {
+    _ = self;
+    _ = decl_val;
     _ = reloc_info;
     _ = @panic("TODO: link/Plan9 getAnonDeclVAddr");
 }
diff --git a/src/link/Wasm.zig b/src/link/Wasm.zig
index 9ae580bb9e..34244d2247 100644
--- a/src/link/Wasm.zig
+++ b/src/link/Wasm.zig
@@ -1679,13 +1679,8 @@ pub fn getDeclVAddr(
     return target_symbol_index;
 }
 
-pub fn getAnonDeclVAddr(
-    wasm: *Wasm,
-    decl_val: InternPool.Index,
-    reloc_info: link.File.RelocInfo,
-) !u64 {
-    // This is basically the same as lowerUnnamedConst except it needs
-    // to return the same thing as `getDeclVAddr`
+pub fn lowerAnonDecl(self: *Wasm, decl_val: InternPool.Index, src_loc: Module.SrcLoc) !codegen.Result {
+    // This is basically the same as lowerUnnamedConst.
     // example:
     // const ty = mod.intern_pool.typeOf(decl_val).toType();
     // const val = decl_val.toValue();
@@ -1694,6 +1689,13 @@ pub fn getAnonDeclVAddr(
     // be used by more than one function, however, its address is being used so we need
     // to put it in some location.
     // ...
+    _ = self;
+    _ = decl_val;
+    _ = src_loc;
+    _ = @panic("TODO: link/Wasm lowerAnonDecl");
+}
+
+pub fn getAnonDeclVAddr(wasm: *Wasm, decl_val: InternPool.Index, reloc_info: link.File.RelocInfo) !u64 {
     _ = wasm;
     _ = decl_val;
     _ = reloc_info;